main: Remove unused variable

This amends commit a6c17fc5.

Change-Id: I365513a9e11e6c07310799f87a4e299cd110dcf3
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/app/main.cpp

@@ -157,9 +157,8 @@ static inline int askMsgSendFailed()
                                  QMessageBox::Retry);
 }
 
-static const char *setHighDpiEnvironmentVariable()
+static void setHighDpiEnvironmentVariable()
 {
-    const char* envVarName = 0;
     static const char ENV_VAR_QT_DEVICE_PIXEL_RATIO[] = "QT_DEVICE_PIXEL_RATIO";
     if (Utils::HostOsInfo().isWindowsHost()
             && !qEnvironmentVariableIsSet(ENV_VAR_QT_DEVICE_PIXEL_RATIO) // legacy in 5.6, but still functional
@@ -168,7 +167,6 @@ static const char *setHighDpiEnvironmentVariable()
             && !qEnvironmentVariableIsSet("QT_SCREEN_SCALE_FACTORS")) {
         QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
     }
-    return envVarName;
 }
 
 // taken from utils/fileutils.cpp. We can not use utils here since that depends app_version.h.
@@ -304,7 +302,7 @@ int main(int argc, char **argv)
 
     Utils::TemporaryDirectory::setMasterTemporaryDirectory(QDir::tempPath() + "/QtCreator-XXXXXX");
 
-    const char *highDpiEnvironmentVariable = setHighDpiEnvironmentVariable();
+    setHighDpiEnvironmentVariable();
 
     QLoggingCategory::setFilterRules(QLatin1String("qtc.*.debug=false\nqtc.*.info=false"));
 
@@ -322,9 +320,6 @@ int main(int argc, char **argv)
 
     loadFonts();
 
-    if (highDpiEnvironmentVariable)
-        qunsetenv(highDpiEnvironmentVariable);
-
     if (Utils::HostOsInfo().isWindowsHost()
             && !qFuzzyCompare(qApp->devicePixelRatio(), 1.0)
             && QApplication::style()->objectName().startsWith(